The invention relates to a vehicle having a main frame on which there is fixed at least one contact element, in particular a wheel, a skid, a caterpillar track or a float, which can be steered by means of an axle pivot steering arrangement, having a tilting frame which is tiltable relative to the main frame by a driver and has a tilt axis, having a steering tube which has a steering axis running obliquely or perpendicularly to the tilt axis, having at least one track rod, and having at least one track rod actuation element.
In particular, on the vehicle the steering tube is likewise tiltable relative to the main frame.
In connection with the invention disclosed in the present application the term “track rod” includes any configuration of a steering transmission element with which a movement of the track rod actuation element is transmitted to the axle pivot steering arrangement of the steerable contact element.
As a precaution it is to be pointed out that in the present case the term “axle pivot steering arrangement” also includes hub centre steering arrangements such as are used, for example, in individual cases on motorcycles.
The track rod actuating element is arranged functionally—in a steering gear—between the steering tube and track rod and transmits a steering movement caused by the driver to the track rod(s), as a result of which the direction of travel of the vehicle is changed via the at least one steerable contact element.
In a vehicle of such configuration the driver can lean, together with the tilting frame, into the curve during driving without the camber of the steerable contact element or the steerable contact elements changing or changing substantially, as is triggered by the steering movement during cornering. Slight changes in camber due to the chassis kinematics are of course nevertheless possible.
If the contact elements are, for example, wheels, and for example fixed via an individual wheel suspension on the main frame with king pin inclination, i.e. a not quite vertical axis, a negligible change in the camber takes place when the wheels are steered in due to the chassis kinematics.
The camber moreover also changes negligibly due to compression and rebound.
A substantial change in the camber during steering into the curve, such as e.g. at an angled position when riding a motorcycle, and an associated reduction in the tyre contact area and in the adhesion between tyre and ground does not take place.
By construction of a tilting frame which is tiltable by a driver relative to a main frame on which the contact elements are fixed, the tilting frame can be tilted by the driver towards the inside of the curve according to the curve radius and the curve speed and thus against the centrifugal force.
By this means on the one hand a substantially more comfortable seating position for the driver is achieved, since he can lean into the curve together with the tilting frame and furthermore the centre of gravity is displaced inwards not only by the weight of the driver, but also by the tilting frame and all the attachments, as a result of which the risk of the vehicle overturning is reduced significantly.
By the feature that the wheels and/or skids are fixed on the main frame such that the camber does not change or changes only negligibly when steering into the curve a maximum contact area between tyre and ground when cornering is also maintained with tyres having a substantially flat tread. Maintaining the maximum contact area between tyre and ground when cornering on the one hand significantly increases safety, since more frictional area is available between tyre and ground. On the other hand the full tread is also available when cornering, as a result of which the tread, which has been optimised by the tyre manufacturer, is also completely available for the drive in the curve.
By the feature that contact elements are fixed on the main frame and a contact element is rotatable and therefore steerable relative to the main frame via a steering arrangement, it is ensured that the advantages described above also apply to the wheels which are rotatable for changing the direction of travel. The wheels here rotate about an axis substantially perpendicular to the direction of the vehicle, so that the camber remains virtually unchanged.
By this construction the main frame with the contact elements arranged thereon is aligned substantially parallel to the surface of the roadway covering, it being possible for the tilting frame with the driver to lean inwards, depending on the curve speed and curve radius. By this means a sensation as when motorcycle riding arises, substantially higher curve speeds being possible due to the contact elements which do not tilt into the curve. The chassis, formed from the main frame and the contact elements arranged thereon, allows a faster and safer cornering because of the maximum contact area between the contact element and roadway covering. Furthermore, the chassis brings about improved drive and braking properties in the curve.
In sloping terrain, such as, for example, in hilly countryside and in the mountains, the vehicle has a particular advantage, since even during travel on a slant relative to the direction of inclination of the terrain, for example travel diagonally uphill or downhill, a relatively comfortable vertical or at least upright sitting position can still be assumed via the tilting frame.
A vehicle having such a construction is known from US 2010/0320023 A1. The drive unit is connected to the main frame in a fixed manner. Due to the high arrangement of the drive combined with the high centre of gravity of the drive, the tendency of the vehicle to overturn when cornering is not substantially reduced.
U.S. Pat. No. 7,946,371 discloses a snowmobile in which the vehicle body including the engine and drive can tilt into the curve relative to the front chassis. The aim here is that the skis attached to the chassis do not run on the edges when cornering.
U.S. Pat. No. 2,643,897 discloses a connecting means between a car body and the wheels, which is said to avoid swaying of the vehicle on an uneven or sloping road.
US 2008/0100018 A1 describes a vehicle suspension system in which the wheels, the passenger section and where appropriate the boot are tiltable relative to the engine and drive section, including the vehicle's suspension.
NL000001005894C discloses a vehicle having a tilting frame which is pivotable horizontally about a vertical pivot axis which is fixed on a main frame and on which track rods to two steerable wheels are fixed. Actuation of the track rods is via rotation of a steering column of the tilting frame, which is fixed to the main frame via a joint. On rotation of the steering column the tilting frame pivots horizontally about the pivot axis, as a result of which the track rods are likewise shifted horizontally in the pivoting direction and cause steering in of the steerable wheels. This complex steering mechanism generates a righting moment on the steering column via the tilting frame during cornering, but not on the tilt of the tilting frame. Tilting of the tilting frame alone brings about no steering movement on the steerable wheels.